1. Field of the Invention
This invention relates to a plugging and centralising device for locating the stem of a prosthesis.
2. Description of the Prior Art
When using cement to locate the stem of a prosthesis in an medullary canal it is usual to plug the lower end of the canal to prevent cement extending along it beyond the stem of the prosthesis.
Such plugs are well known, for example as shown in GB 2 017 503 which shows a plug with ranks of resilient lugs which jam against the side wall of the cavity to prevent the bone cement from escaping downwards. Another type of plug is shown in GB 2 047 541 which has a mid-portion which serves as a seal against the walls of the canal and an upper portion which is open ended to define a recess formed by a series of petals which are intended to prevent extrusion of the plug back out of the open canal. Another plug is show in U.S. Pat. No. 5,766,178 which has deformable flanges.
It is also known to provide a centraliser for the distal end of the stem of a prosthesis, for example as shown in U.S. Pat. No. 5,092,892 in which there are resiliently deformable fins which engage the wall of the canal and an annular body portion which locates the tip end of the stem of the prosthesis. Another type of centraliser is shown in GB 1 409 053 which has an annular base member with a number of spring members extending therefrom. The annular portion receives the free end of the stem and slides only part way along it and the spring members act to centraliser the stem in the canal.
Plugs and centralisers are frequently used together.